The largest animal protection organization in the United States, Humane Society of the United States (HSUS) works to preserve wildlife and wilderness, save endangered species, and promote humane treatment of all animals. Formed in 1954, HSUS specializes in education, cruelty investigations and prosecutions, wildlife and nature preservation, environmental protection, federal and state legislative activities, and other actions designed to protect animal welfare and the environment.

Major projects undertaken by HSUS in recent years have included campaigns to stop the killing of whales, dolphins, elephants, bears, and wolves; to help reduce the number of animals used in medical research and to improve the conditions under which they are used; to oppose the use of fur by the fashion industry; and to address the problem of pet overpopulation.

The group has worked extensively to ban the use of tuna caught in...